Maj. Gen. Geoffrey D. Miller, a central figure in the U.S. detainee-abuse scandal, this week invoked his right not to incriminate himself in court-martial proceedings against two soldiers accused of using dogs to intimidate captives at the Abu Ghraib prison in Iraq, according to lawyers involved in the case.

The move by Miller -- who once supervised the U.S. detention facility at Guantanamo Bay, Cuba, and helped set up operations at Abu Ghraib -- is the first time the general has given an indication that he might have information that could implicate him in wrongdoing, according to military lawyers.

Harvey Volzer, an attorney for one of the dog handlers, has been seeking to question Miller to determine whether Miller ordered the use of military working dogs to frighten detainees during interrogations at Abu Ghraib. Volzer has argued that the dog handlers were following orders when the animals were used against detainees.

Maj. Michelle E. Crawford, a defense lawyer representing Miller, said the general decided not to answer further questions because he has "been interviewed repeatedly over the last several years" about his role at Guantanamo Bay and his visit to Iraq and he stands by his many statements to Congress, Army investigators and lawyers.

Miller's "choice to no longer answer the same questions . . . was based on the advice of counsel and includes the fact that he has already, and repeatedly, answered all inquiries fully," Crawford said.

Miller's decision came shortly after Col. Thomas M. Pappas, the commanding officer at Abu Ghraib, accepted immunity from prosecution this week and was ordered to testify at upcoming courts-martial. Pappas, a military intelligence officer, could be asked to detail high-level policies relating to the treatment of detainees at Abu Ghraib.

He also could shed light on how abusive tactics emerged, who ordered their use and their possible connection to officials in Washington, according to lawyers and human rights advocates who have closely followed the case. Pappas has never spoken publicly. Crawford said Miller was unaware of Pappas's grant of immunity. "This could be a big break if Pappas testifies as to why those dogs were used and who ordered the dogs to be used," said Michael Ratner, president of the Center for Constitutional Rights. "It's a steppingstone going up the chain of command, and that's positive. It might demonstrate that it wasn't just a few rotten apples."

Pappas's attorney, Maj. Jeffery D. Lippert, said yesterday that Pappas would not comment. But he added in an e-mail that "the Commanding General of the Military District of Washington has ordered Col. Pappas to testify if called as a witness in pending courts-martial, and granted him testimonial immunity to facilitate his appearance as a witness."

Miller invoked his military Article 31 rights through his Army lawyer on Tuesday, after a Navy judge in the Military District of Washington ruled that lawyers defending the two dog handlers could interview Miller this week. Article 31 rights are almost identical to those afforded civilians by the Fifth Amendment, and invoking them does not legally imply guilt. Miller now will not meet with the defense lawyers.

Eugene R. Fidell, a Washington expert in military law, said that Miller's decision is "consistent with his being concerned that he may have some exposure to worry about." Fidell added: "It's very unusual for senior officers to invoke their Article 31 rights. The culture in the military tends to encourage cooperation rather than the opposite."

Miller has long been in the spotlight of the Abu Ghraib abuse investigations, largely because he was sent to the Iraq prison in August and September 2003 with the goal of streamlining its intelligence-gathering operations, using Guantanamo Bay, commonly called "Gitmo," as a model. Officers at Abu Ghraib have said that Miller wanted to "Gitmo-ize" the facility, and that harsh tactics migrated from the Cuba facility via "Tiger Teams" that Miller sent to Iraq as trainers.

Photographs documenting a wide array of abuse against dozens of detainees at Abu Ghraib in late 2003 were turned over to military investigators in January 2004. The photographs were revealed publicly in April 2004, and seven low-ranking military police soldiers have taken most of the blame for the treatment of captives, which included sexual humiliation, stress positions and beatings. All seven were convicted on various charges, the most serious of which led to a 10-year prison sentence for Pvt. Charles A. Graner.

In an interview with defense attorneys for those MPs in August 2004, Miller said he never told Pappas to use dogs in questioning detainees. Photos of the dog handlers scaring detainees at Abu Ghraib were among the most notorious to emerge from the prison. Dogs were also used at Guantanamo Bay.

"At no time did we discuss the use of dogs in interrogations," Miller said, according to a transcript.

Volzer, who represents Sgt. Santos A. Cardona, one of the military dog handlers charged with abuse, said he believes the grant of immunity to Pappas will essentially clear his client, because Pappas already has admitted in administrative hearings that he improperly ordered the use of dogs. Volzer said he believes that Pappas was taking direction from Miller, and that Miller was acting on instructions from Defense Department officials. Cardona and Sgt. Michael J. Smith are scheduled to be tried in separate courts-martial in February and March.

"I think the command is hiding something, and I think what they're hiding is material that is exculpatory that says the interrogation techniques were approved by powers above General Miller," Volzer said. "Having Pappas available to testify may have given Miller the impression that he is next to be accused of doing something inappropriate or giving inappropriate orders."

Miller, now based at the Pentagon as a senior official managing Army installations, was recommended for administrative punishment for his alleged mishandling of interrogations of a valuable detainee in Guantanamo Bay. But high-ranking military officials have declined to impose the penalty. The detainee was subjected to a number of abuses that mirrored the ones that later emerged in the Abu Ghraib photographs.

Maj. Christopher Graveline, who has prosecuted several of the Abu Ghraib abuse cases, said yesterday that Pappas might be called to testify in upcoming courts-martial, but declined to comment on "any current or future prosecutions."

Asked whether prosecutors are looking at additional charges arising out of the Abu Ghraib investigation, Graveline said: "We're taking it where the evidence leads it."